1. Field
This disclosure relates generally to accelerometers, and more specifically, to a caddie-corner single proof mass three-axis (XYZ) micro electromechanical system (MEMS) transducer.
2. Related Art
FIG. 1 is a perspective view diagram of a portion 10 of a three-axis (XYZ) transducer/accelerometer having a known rectangular shaped proof mass 12. The rectangular shaped proof mass 12 is characterized by width and length dimensions, indicated by reference numerals 14 and 16, respectively. A portion of proof mass 12 along the length dimension 16 comprises an extended portion 18, wherein the extended portion extends along the total width 14. Extended portion 18 provides for an added weight to the proof mass 12 for the z-sense direction.
The proof mass 12 is coupled to a plurality of springs, as indicated by reference numerals 20, 22, 24, and 26. The springs couple to an underlying substrate (not shown) and allow movement of the proof mass 12 in the X, Y, and Z directions. The springs are generally located within a main region of the proof mass 12 defined by the width dimension 14 and by a portion of the length dimension 16 not including the extended portion 18. The three axes X, Y, and Z are indicated by reference numerals 28, 30, and 32 respectively. Plus (+) and minus (−) signs have been illustrated to indicate an example of a positive or negative direction with respect to a given acceleration force along a respective sense axis.
The current proof mass design suffers from several shortfalls. For example, the current proof mass is limited in its z-sense axis roll-off frequency, and its larger overall g-cell area/size. It's linearity may also be able to be improved upon. In addition, the z-sense pivot axis is not well defined, wherein the z-sense pivot axis is more of a virtual sense pivot axis, indicated by reference numeral 34, which is subject to changing its position, for example, within a range from the axis indicated by reference numeral 36 to the axis indicated by reference numeral 38. Such a virtual z-sense pivot axis is undesirable.
Accordingly, there is a need for an improved method and apparatus for overcoming the problems in the art as discussed above.